README: Advise 'go get' over 'go install'
README: Advise 'go get' over 'go install'

This will automatically fetch deps.

wfxiang08/livegrep,lekkas/livegrep,wfxiang08/livegrep,wfxiang08/livegrep,paulproteus/livegrep,lekkas/livegrep,lekkas/livegrep,paulproteus/livegrep,lekkas/livegrep,lekkas/livegrep,wfxiang08/livegrep,paulproteus/livegrep,wfxiang08/livegrep,paulproteus/livegrep,lekkas/livegrep,paulproteus/livegrep,wfxiang08/livegrep,paulproteus/livegrep